Question about my gear

[:1]I have a lot of PvP gear, but I couldn't resist swapping about my Brutal Gladiator's Dreadplate Helm for this clothie green I got in Northrend. I'm sorry, but it matches my gear perfectly (uncommon for quest greens) and I've always wanted a hood. I don't think I can transmog my plate helm thing down... Is it ok for me to wear this? :(
How cute. :)

You will take a DPS loss, as that helm is pretty much like not wearing a helm at all. However, if you're just solo questing it's okay. if you're doing 5-mans or PvP you may want to wear your "proper" helm and put the hood back on when you get out.

You might want to pull your green starting gear out; it included a plate hood (Acherus Knight's Hood) that should match the level 70 PvP set and looks awesome. If you vendored it, you can go to Acherus and buy a new one from the abomidation quartermaster, Ozrog, on the second floor, the one with the runeforges and training dummies.
/facepalm